ETP

[Tonic Please]

Last question for today.

How is an ETP displayed on the ND? Do you enter a lat/long fix and put a little ring around it?

Thank you.

[aerobat77]

uy,,, the mighty equi time point. well, its dependant on the fmc type . on the honeywell installed on the bae146 you can highlight it from the submenu of nearest airports or the dest/arrival airport.

but remember that at least the bae146 fmc only calculates the distance and does not care about actual winds when it comes to etp.

cheers

[Tonic Please]

I know I sound incredibly ignorant, and whilst I've gone through the training and studying of this kind of thing (a few years back when I was flying), for commercial operations, it all seems very unnecessary (armour on) :suspect:

Imagine London to, say, anywhere about 3 hours away, Eastern Europe-ish. ETP, it seems, would be roughly in the middle, dependant on winds. You could plop in (if it isn't provided automatically which helps) a fix about midway (minus all the complex calculation hoohaa, and simply make a decision there and then?

Second, surely it's incredibly unlikely that something will go wrong requiring such a return/continue scenario, but so close the to ETP is even MORE unlikely, statistically speaking. Most things in aviation are based on logic/statistics/likelihood, so it seems to my ignorant non-airliner brain that an ETP point calculation is a little OTT?

Is that how you feel when flying? If a situation arose requiring a turn-back or continue, you could look at DTG to dest, DTG to departure point and make a quick decision without all the calculations!

Is ETP really that important?

Thank you :)

[aerobat77]

hehe-basicly you are pretty right here- the etp has in real life very little value , even when it should be possible to discuss it to death by theroretical means.

i also remember the manual calculation, even considering wind and calculating by nautical air and nautical ground miles and i hated it, further was never in a situation when this would help with a decision.

the pure etp does not take into account if the next airport is your best option in regards to emergency facilities, runway lenght, descend path and much more, it does not take into account if going there will result in an overweight landing, it does not even take into account the wind when calculated by fmc. its just a basic information.

depending on what why and where happened its alsways a manual decision what to do.

cheers !

[TopBunk]

When flying around Europe with an airport suitable for any aircraft every 200 nm or so I would agree that ETP's are of little relevance.

Now think about crossing the Atlantic, Pacific, desert region etc et night. There may be no suitable open airport for 2 hours or more.

Believe me, you want to know where you will go at any point of time should a 'Land ASAP' event happen. You will be always aware of the latest wx forecast etc. On the B747-400 the FMC allows you to put in a time as a fix, this then appears on the ND as a circle with the time next to it.

Drawing range circles around airports is also useful, iirc the max range circle on the B747-400 is 511nm and the max range scale on the ND is 640nm.

This facility is also useful for letting you know when it is your turn for the bunk :ok:

[GlueBall]

Imagine London to, say, anywhere about 3 hours away, Eastern Europe-ish. ETP, it seems, would be roughly in the middle, dependant on winds. You could plop in (if it isn't provided automatically which helps) a fix about midway (minus all the complex calculation hoohaa, and simply make a decision there and then?

Why would you need an ETP along a route with airports all around....? :confused:

[Tonic Please]

Very good and clear responses. Thanks yet again.

Valid point re. Europe and airports all round. I guess I was talking about distance rather than geographical location.

I guess my absolutely final question would refer to my RTE2 page question but involves the ETP:

Would you constantly update RTE2 as you go on so that it is related in some way to an ETP? Further, can you update an ETP from a new airfield en-route?

I imagine London to Hong Kong or some such - or Japan to New Zeland/Buenos Aires/Rio kind of flights). Could you 'reset' your ETP (along with a revised RTE2 page) on passing a possible en-route alternate and consider that your new 'base' or 'imaginary departure airfield' for want of a better word?

I hope I make myself clear.

Dan

[Denti]

Believe me, you want to know where you will go at any point of time should a 'Land ASAP' event happen.

Don't you have a FMC page for that with list of the closest airports? The 737 has, including info on mileage, fuel remaining at destination and a one click weather request for any thus selected airport.

However being able to enter a time directly as waypoint can be pretty useful, sadly we do not have that.

Apart from that the fix pages are a nice tool for whatever you want, be it to draw nice circles in the middle of nowhere or remind one of a fuel check/reporting point or of course an ETP if you happen to need that (never did on the 737 in europe/northern africa/UAE).

[bucket_and_spade]

An ETP is only relevant in ETOPs or similar operations. Over Europe, I can't fathom why you'd bother/what value it adds. It's just a distraction and would reduce your SA as you'd probably never bother looking at what suitable airports are around you!

The ETP is important in ETOPs planning (usually the last ETP on a route, if more than one exist, has a fuel requirement associated with it - the Critical Fuel Requirement. We must have enough fuel at this point, on our airfraft type, to depressurise and fly to a suitable alternate, in the prevailing weather, at 10,000', with enough for 15 minutes holding at 1500' overhead).

It's also useful in the air - it gives you an awareness of whether you're carry-on-minded or turn-back-minded in a time-critical scenario over lots of water. We put the lat/long as a 'floating waypoint' on the end of the route so it displays on the ND/HSI.

aerobat77,

A proper ETP, rather than just a 'halfway point' will take in to account the wind.

Hey Denti,

Isn't there a predicted ETA line on your fix pages to put times in? I'm surprised - thought the 737 and 757 FMCs shared a lot of commonality. We don't get the 1-click weather reports though - very decadent! :O

Cheers!

B&S

[TopBunk]

Denti
Don't you have a FMC page for that with list of the closest airports? The 737 has, including info on mileage, fuel remaining at destination and a one click weather request for any thus selected airport.
No!

I remember that FMC page from my days on the 737-400 20 years ago and thought that it was cool, albeit iirc, just giving DTG and fuel on arrival, uncorrected for wind, so not really ETP information.

As I said before, there is also airport opening hours to consider, something not usually an issue in European daytime flying which the majority of it is.

[Tonic Please]

Very interesting and informative. Thank you to all. I shall now try it out for a tad more realism.

Floating fixes - nice terminology :D

[Artificial Horizon]

Certainly on the A320 there is an ETP page under the DATA menu. You can select any two airports and it will display a ring on the green line at the appropriate point. When I flew in Europe the ETP had little relevance at all due to the abundance of suitable airports everywhere.

Now that I frequently fly across the Pacific 'ETP's' become very, very important. The big difference though is at the flight planning stage ETP's are worked out taking into account, winds, fuel, engine out scenarios, depressurisations etc and a list of ETP's published for your flight in the form of LAT's and LONG's. These are then entered as new waypoints and placed into the flight plan. It is amazing how much these differ from the FMGS calculated position which assumes programmed winds and two engines operating.

[Tonic Please]

Hi,

May I ask how and who works these out for Pacific flights? What about West Coast to Hawaii?

Thanks :)

[zlin77]

On The B777 on the FIX pages in the FMC I just enter range rings that correspond to the data supplied on our flight plans....and as if my magic they intercept our track, however ETOPS planning is just an excuse to get airborne, normally in flight any major emergency Fire/Failure etc. our QRH says.."Land at the nearest suitable airport"..this does not mean fly for another 3 hours to a planning airport if a suitable airport is closer, who knows it might nearly be below you!...North Pacific Operations can be a little tricky, I operated out to 207 minutes using say RJCC & PANC with a previous operator and sometimes nothing else was suitable.....

[Spooky 2]

West coast to the Hawaiian islands require 180 ETOPS. (2 Eng.) If your departing Southern California your ETP airports will usually be KSFO and PHTO but there is always the exception with unusual winds that might bring you back to KLAX. Leaving KSEA or KPDX you would have KPDX as your first ETP alternte and then for a period time KSFO would be the active alternate. Finally PHOG would show up as the final ETP alternate. Again unusual winds can cause these alternate to chnange.

Some Honeywell FMC's will allow you to display the Lat/Long on the FIX page, others will not. You can always build the ETPs on the ROUTE Page 2 in that case. The 737 uses a Smiths FMC so I don't know what works best for that airplane.

Use of a plotting chart is beneficial in plotting both the ETPs along with the ETP entry points.

[ImbracableCrunk]

On the 737 we simply enter EEP, EXP and CP1 in as a temp nav data. I've heard some airlines just put them in as legs after a disco after the dest airport.

[Spooky 2]

Yes, putting the ETP at the very end of the LEGS page, after a discontinuty works as well.

[Tonic Please]

All very insightful. Thanks very much!

[latetonite]

Go take the ETP from your Flight Plan. Create a waypoint in the FMC along with the Etops Entry point, and Exit point, insert them in the legs page, have a look in plan mode if it all makes sense, and ready.

[latetonite]

It shows up in the legs and prog page as another waypoint. Do not forward your estimates to ATC though.

[Checkboard]

http://www.pprune.org/tech-log/9934-pnr-usage.html
Thread where I explain some manual calculation methods & shortcuts for ETPs & PNRs in the cockpit.

http://www.pprune.org/tech-log/10820-pnr-calculation.html
Thread were Flat Side Up explains an excellent method for PNR calculation which has one slide rule set up which displays Time, Distance and Fuel Burn.

[Young Paul]

On the version of the Airbus FMGC that we are using at the moment, you can work out an ETP for any two points. The default ETP is from departure to destination, and it draws a nice circle there. But you can replace the departure and destination in the relevant page on the MCDU with any positions (not just waypoints) you choose, and it will redraw your circle.

This is most useful for ETOPS, or ETOPS-like operations (the only time I really ever bother is to work out where the nearest usable airfield is on a long over-water sector - not for single engine work, but for NO engine consideration, I want to be as close to the possibility of rescue as possible). Yes, it's a bit arbitrary - but then, so, really is the idea of having an engine failure between V1 and V2, or the net flight path.

[misd-agin]

SOP - not allowed to build fixes into, or alter, Rte 1.

Solution(technique) - Rte Copy Rte 1, build ETP's as along track fixes on Rte 2, display Rte 2.

Fix page - enter /511 to display circles around divert fields. Helps with visual situation awareness.

Another technique - On Rte 2 build a route from #1 divert field, to ETP #1, to divert field #2, to ETP #2, to final divert field. Display Rte 2. You end up with blue lines (Rte 2 not executed) showing the divert sectors.

Another technique - ETP is X miles short of 30W? Enter fix or lat/long, if able, into Fix page and put a circle X miles around the fix.

Another technique - Enter ETP time in 6R of Fix page.

[Spooky 2]

Well I might be reading something that has been lost in the translation but I would never put an ETP on the LEGS so as to cause the FMC to look at that LAT/LONG as an active waypoint. Bad procedure and if you are using ADS-C I would expect a call from the controller asking where you might be going? If that waypoint was not a part of your ICAO flight plan, then it should not find it's way onto the LEGS page.

[ImbracableCrunk]

Well I might be reading something that has been lost in the translation but I would never put an ETP on the LEGS so as to cause the FMC to look at that LAT/LONG as an active waypoint. Bad procedure and if you are using ADS-C I would expect a call from the controller asking where you might be going? If that waypoint was not a part of your ICAO flight plan, then it should not find it's way onto the LEGS page.
Yep, same here. But it could be that the "same here" is the same "here."

[latetonite]

Your ETP, etops entry and exit points are of course on your flight routing, not interfering with your routing. If a controller asks you what you are doing, you are probably in radar contact. I have to see the first Etops Entry point where you are still under radar coverage.

[ImbracableCrunk]

Your ETP, etops entry and exit points are of course on your flight routing

Well, they certainly are if you put them on your legs page. However, you lose your cross-checking ability by doing this.

[latetonite]

Would you care to explain x-checking issue bit more deep?

[Spooky 2]

ADS-C for all intent and purposes is even better than "Radar Contact" in this case. The controller, Shanwick for instance, can see what Lat Long your FMC is going to. If it's not part of your ICAO flight plan then you are doing something wrong. ETP's & EEP's do not belong on the LEGS page of the FMC....period!

[Pontius's Copilot]

More mundanely, but more important for those of us that do not zoom around in spaceships, ETP is potentially a lifesaver for -
- Aircraft without drop-down oxygen for pax when transiting an MSA above FL140;
- When the OEI service ceiling is such that you would need to know the shortest/quickest track to a lower MSA (Drift-down).

[Tonic Please]

All noted. Thanks a lot for the extended discussion.

[Young Paul]

Um ... hadn't considered that about active waypoints, and can't remember offhand how exactly it behaves. However, I'm not convinced that an FMGC derived position - can think also of a time marker, TOD or step-climb marker - would actually show as the next active waypoint on ADS-C.

And isn't part of the point about MNPS airspace (which is when ETP is most useful) that you don't have radar monitoring?

I have to say that I have very limited experience here, so these are genuine questions.

[latetonite]

Spooky, how and when you perform mandatory ETOPS checks? By monitoring the IRS displays? And what about the abeam points you want to have displayed when cleared "direct to"? The FMC is a tool and competent pilots use it as such.
The Enty, ETP`s and Exit points are in some companies mandatory inserting points, ie it is a SOP to insert them.

[galaxy flyer]

With a triple FMS installation, we enter the ETPs in the unpaired FMS, the PM can display the ETPs on his ND or monitor #3 FMS for position.

I'm trying to figure out how you can enter ETPs, as waypoints, when they are NOT on cleared routing. Yes, they along track, but still not points on the LEGS page.

GF

[Matt101]

ETOPS wise...

We don't insert them in the Primary flight plan. Several options for displaying them once you've entered them as a pilot waypoint though. Secondary FP (Diversion planned from an ETP set up there anyway). Pressing the WPT button on your EFIS control or using the L1 key on the MCDU and entering the most relevant points as a REF FIX. Airbus stuff.

Different strokes different folks though I guess.

ETP on normal flights - Airbus makes it quite easy to display an FMGC created ETP on your route for any two points. I'm rather new so find it a useful tool when adhering to SOP's and giving the occasional "if the proverbial hits the fan now this is where I'd go and after that here" brief. But that's just me.

[misd-agin]

GF - it appears from the discussion that some operators enter ETP's into their LEGS pages per their SOP's.

Our SOP prohibit changing the active RTE. RTE 2 is available and can be displayed without activating. That's where you can enter ETP's or other along track fixes.

Most guys just keep track of the ETP time and/or distance, and don't bother entering along track fixes. Technique.

Older generation Airbus FMC's did not have RTE 2 capability. Not sure if the newer Airbus FMC's have RTE 2 capability.

[galaxy flyer]

misd-agin

Oh, I understand that they can be put into the active flight plan, but why would you do so considering you would be flying to waypoints not as cleared. While, yes, they should be on the route.

GF

[Young Paul]

Does people's aversion to non-active-waypoints also cover abeam positions generated by the FMGC? Personally, I always thought that there was no point in chucking information away ....

[wiggy]

Does people's aversion to non-active-waypoints also cover abeam positions generated by the FMGC?

Not sure about FMGCs but in the case of this Boeing, FMC user abeams are also a "no no" in an ADS environment - for all the reasons previously mentioned ( corrupt ADS position reports).

If abeams are needed the teaching is to display Route 2, the non-active route, on the Navigation Display (ND)- this of course assumes you've copied the original route into Route 2 in the first place:*, or use the FMC fix pages and/or waypoint/station function on the ND.

[5LY]

GF. To answer your question about entering an EEP or ETP on the legs page, of course you're right, you don't ever want one of them becoming the active wpt. If your equipment has limited capabilities, one way to do it is to put it at the end of your flight plan on the legs page after the destination and after a discontinuity. If "floats" there, and is visible on your nav display as you go by it, but never becomes the active wpt. It has no effect on your flight plan total dist. and fuel calc's. Used to do this on the B757 with it's basic FMC.

If your equipment is capable, then the fix page is the place to put them either as Lat. and Long. or with distance rings. (Usual B777 method).

[Longjon]

Apart from the ADS is there any other reason why the EEP ETP EXP should NOT be part of the FMS flight plan.?
Thanks

[Desert185]

Just for clarification on how an ETP2/3 (in my case) is defined...

1. Use the wind at the altitude capability and half the distance from the ETP to the desired ETP airport to determine the ETP plot position, i.e. GSR and GSC. Having the appropriate MB charts onboard are a good reference, otherwise how would you know the winds along the ETP2/3 course at the required performance FL? It's a ballpark figure, but still as accurate as you can get. Accuracy still counts, right?

2. Use two or three engine TAS and FL as appropriate.

3. ETP, because of all the obvious variables, is just an estimated position, but it can be a valuable tool should it be necessary to know.

4. Never having really used it is not an excuse or for not plotting an ETP overwater. :=

Just my old-school, two cents after manually plotting and training them for years. Adjust your two-motor, ETOPS flying machines accordingly.

[Longjon]

You enter the coordinates and stow it as a stored WPT then you can either recall it on by pressing WPT on on the EFIS panel or else enter it on the FMS flight plan
.....this is not recommended.but bible s you ETA and fuel predictions.

[EMIT]

See this exact same discussion in the topic that ran less than 2 weeks ago ...

http://www.pprune.org/tech-log/513985-etops-points-fms-flight-plan.html

It's on page 3 of this tech log now.

Happy reading:)